If you aren't able to connect in Firefox, but can connect with other programs, the most common cause is a firewall. See [[Firewalls]] for instructions on configuring firewalls.
Other possibilities for broken connections include:
* Proxy settings can be misconfigured. Check these the [http://support.mozilla.com/en-US/kb/Options+window+-+Advanced+panel Advanced panel of the Options window].
* You are in offline mode. Make sure "Work offline" in the File menu is ''unchecked''.
For other causes, see [[Error loading web sites]]